1. Field of the Invention
The present invention relates to portable game machines performing display on liquid crystal displays (LCDs), and more particularly to a portable game machine, in which an operating temperature and a power supply voltage are detected for adjusting a driving voltage for an LCD.
2. Description of the Background Art
LCDs which display screens with low power consumption are suitable display devices for portable game machines. Recently, as a type of LCD capable of color display, an LCD of Electrically Controlled Birefringence method (hereinafter referred to as ECB) has become commercially practical. The ECB-LCD performs color display by utilizing a variation of birefringence characteristics in a liquid crystal layer. Such variation is caused by changing a tilt angle of liquid crystal molecules by changing a voltage applied to the liquid crystal layer. Since the ECB-LCD does not require a backlight, color display can be realized with low power consumption.
On the other hand, the ECB-LCD has a characteristic that the display color varies depending on an operating temperature. This is because the birefringence characteristic of liquid crystal layer changes as the operating temperature changes. FIG. 13 shows the exemplary relation between temperatures/voltages and display colors in the ECB-LCD. As the voltage increases, the display color of ECB-LCD changes from green to purple, then to yellow, for example. The display color of the ECB-LCD also varies depending on the variation in operating temperature.
In the portable game machine adopting the ECB-LCD, it is also required to correctly display predetermined colors regardless of the operating temperature variation. For example, in a portable game machine where characters appear in a game played therewith, an LCD is required to display the characters with respective predetermined colors. The operating temperature of the portable game machine, however, varies depending on use conditions, and accordingly, the display color of ECB-LCD varies. Therefore, in order to achieve correct color display on the ECB-LCD, the operating temperature of the LCD is detected and the driving voltage therefor is adjusted based on the detected temperature value.
Further, in the portable game machine, the driving voltage for the LCD is generated by raising a power supply voltage supplied by a battery. The display color of the ECB-LCD is therefore vulnerable to power supply voltage fluctuations. It is thus required to detect the power supply voltage, as well, and adjust the driving voltage for the LCD based on the detected voltage value in order to correctly display colors on the ECB-LCD.
As stated above, in the portable game machine adopting the ECB-LCD, the operating temperature of the LCD and the power supply voltage should be detected for correct color display. The detected temperature and voltage are utilized to control the display color on the ECB-LCD but not to control the contents of games.
Therefore, an object of the present invention is to provide a portable game machine with more fun by reflecting, to the contents of a game, a temperature and a voltage which are detected to control a display color on an LCD .
The present invention has the following features to achieve the object above.
A first aspect of the present invention is directed to a portable game machine performing display on an LCD, comprising:
the LCD for displaying a character data item;
an LCD driving part for driving the LCD;
a temperature detection part for detecting an operating temperature of the LCD;
a voltage detection part for detecting a power supply voltage being supplied;
a program storage part for storing a program;
a character data storage part for storing the character data item; and
a control part for calculating, following the program stored in the program storage part, a driving voltage in the LCD driving part based on the temperature detected by the temperature detection part and the voltage detected by the voltage detection part, and adjusting the driving voltage so that at least a part of the character data item is displayed with a predetermined color.
As described above, in the first aspect, the driving voltage for the LCD is adjusted based on the detected temperature and voltage, and a part of the character data item is displayed with the predetermined color, thereby enabling the display of a character on the LCD with the color unique thereto.
The character data item may be set with predetermined colors on each dot basis, and the driving voltage in the LCD driving part may be so controlled that the predetermined colors are displayed on the dot basis based on the detected temperature and voltage. Alternatively, a plurality of character data items may be stored and a character data item selected therefrom based on the detected temperature and voltage may be displayed on the LCD. In such case, each of the character data items corresponds to at least one of a temperature value and a voltage value, and is selected based on the detected temperature and voltage. By reflecting the detected temperature and voltage to the contents of a game and to the selection of a character, the game becomes more fun and also the status of the game machine can be easily known.
Also, a sound storage part may be further provided, and a sound data item selected based on the detected temperature and voltage may be outputted. This also increases fun of the game. Furthermore, the program storage part, the character data storage part, and the sound data storage part may be structured as being detachable from the portable game machine. Thereby, various games can be played with the same game machine only by changing the recording mediums.
A second aspect of the present invention is directed to a portable game machine performing display on an LCD, comprising:
the LCD on which a display color varies depending on a temperature and a voltage;
an LCD driving part for driving the LCD;
a temperature detection part for detecting an operating temperature of the LCD;
a voltage detection part for detecting a power supply voltage being supplied;
a character data storage part for storing a character data item for a game display; and
a control part for reading the character data item stored in the character data storage part and controlling a driving voltage in the LCD driving part based on the temperature detected by the temperature detection part and the voltage detected by the voltage detection part so that the character data item is displayed on the LCD with at least a part of the character data item changed by color.
As described above, in the second aspect, the driving voltage for the LCD is adjusted based on the detected temperature and voltage, and a character is displayed with at least a part of the character being changed by color, thereby enabling correct color display even on the LCD on which the display color varies depending on a temperature and a voltage. At the same time, by reflecting the detected temperature and voltage to the contents of a game and the display colors, the game becomes more fun.
A plurality of the character data items may be set with predetermined colors on a dot basis, and the driving voltage may be so controlled, based on the detected temperature and the detected voltage, that each dot of the character becomes the predetermined color.
These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.